Remove bucketOrd field from InternalTerms and friends (elastic#118044)

The field bucketOrd is only used for building the aggregation but has no use after that.

server/src/main/java/org/elasticsearch/search/aggregations/BucketOrder.java

@@ -12,6 +12,7 @@
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.search.aggregations.bucket.MultiBucketsAggregation.Bucket;
+import org.elasticsearch.search.aggregations.bucket.terms.BucketAndOrd;
 import org.elasticsearch.search.aggregations.support.AggregationPath;
 import org.elasticsearch.xcontent.ToXContentObject;
 
@@ -20,13 +21,12 @@
 import java.util.Comparator;
 import java.util.List;
 import java.util.function.BiFunction;
-import java.util.function.ToLongFunction;
 
 /**
  * {@link Bucket} ordering strategy. Buckets can be order either as
  * "complete" buckets using {@link #comparator()} or against a combination
  * of the buckets internals with its ordinal with
- * {@link #partiallyBuiltBucketComparator(ToLongFunction, Aggregator)}.
+ * {@link #partiallyBuiltBucketComparator(Aggregator)}.
  */
 public abstract class BucketOrder implements ToXContentObject, Writeable {
     /**
@@ -102,7 +102,7 @@ public final void validate(Aggregator aggregator) throws AggregationExecutionExc
          * to validate this order because doing so checks all of the appropriate
          * paths.
          */
-        partiallyBuiltBucketComparator(null, aggregator);
+        partiallyBuiltBucketComparator(aggregator);
     }
 
     /**
@@ -121,7 +121,7 @@ public final void validate(Aggregator aggregator) throws AggregationExecutionExc
      * with it all the time.
      * </p>
      */
-    public abstract <T extends Bucket> Comparator<T> partiallyBuiltBucketComparator(ToLongFunction<T> ordinalReader, Aggregator aggregator);
+    public abstract <T extends Bucket> Comparator<BucketAndOrd<T>> partiallyBuiltBucketComparator(Aggregator aggregator);
 
     /**
      * Build a comparator for fully built buckets.

server/src/main/java/org/elasticsearch/search/aggregations/InternalOrder.java

@@ -15,6 +15,7 @@
 import org.elasticsearch.common.logging.DeprecationLogger;
 import org.elasticsearch.search.aggregations.Aggregator.BucketComparator;
 import org.elasticsearch.search.aggregations.bucket.MultiBucketsAggregation.Bucket;
+import org.elasticsearch.search.aggregations.bucket.terms.BucketAndOrd;
 import org.elasticsearch.search.aggregations.support.AggregationPath;
 import org.elasticsearch.search.sort.SortOrder;
 import org.elasticsearch.search.sort.SortValue;
@@ -30,7 +31,6 @@
 import java.util.List;
 import java.util.Objects;
 import java.util.function.BiFunction;
-import java.util.function.ToLongFunction;
 
 /**
  * Implementations for {@link Bucket} ordering strategies.
@@ -63,10 +63,10 @@ public AggregationPath path() {
         }
 
         @Override
-        public <T extends Bucket> Comparator<T> partiallyBuiltBucketComparator(ToLongFunction<T> ordinalReader, Aggregator aggregator) {
+        public <T extends Bucket> Comparator<BucketAndOrd<T>> partiallyBuiltBucketComparator(Aggregator aggregator) {
             try {
                 BucketComparator bucketComparator = path.bucketComparator(aggregator, order);
-                return (lhs, rhs) -> bucketComparator.compare(ordinalReader.applyAsLong(lhs), ordinalReader.applyAsLong(rhs));
+                return (lhs, rhs) -> bucketComparator.compare(lhs.ord, rhs.ord);
             } catch (IllegalArgumentException e) {
                 throw new AggregationExecutionException.InvalidPath("Invalid aggregation order path [" + path + "]. " + e.getMessage(), e);
             }
@@ -188,12 +188,13 @@ public XContentBuilder toXContent(XContentBuilder builder, Params params) throws
         }
 
         @Override
-        public <T extends Bucket> Comparator<T> partiallyBuiltBucketComparator(ToLongFunction<T> ordinalReader, Aggregator aggregator) {
-            List<Comparator<T>> comparators = orderElements.stream()
-                .map(oe -> oe.partiallyBuiltBucketComparator(ordinalReader, aggregator))
-                .toList();
+        public <T extends Bucket> Comparator<BucketAndOrd<T>> partiallyBuiltBucketComparator(Aggregator aggregator) {
+            List<Comparator<BucketAndOrd<T>>> comparators = new ArrayList<>(orderElements.size());
+            for (BucketOrder order : orderElements) {
+                comparators.add(order.partiallyBuiltBucketComparator(aggregator));
+            }
             return (lhs, rhs) -> {
-                for (Comparator<T> c : comparators) {
+                for (Comparator<BucketAndOrd<T>> c : comparators) {
                     int result = c.compare(lhs, rhs);
                     if (result != 0) {
                         return result;
@@ -299,9 +300,9 @@ byte id() {
         }
 
         @Override
-        public <T extends Bucket> Comparator<T> partiallyBuiltBucketComparator(ToLongFunction<T> ordinalReader, Aggregator aggregator) {
+        public <T extends Bucket> Comparator<BucketAndOrd<T>> partiallyBuiltBucketComparator(Aggregator aggregator) {
             Comparator<Bucket> comparator = comparator();
-            return comparator::compare;
+            return (lhs, rhs) -> comparator.compare(lhs.bucket, rhs.bucket);
         }
 
         @Override

server/src/main/java/org/elasticsearch/search/aggregations/bucket/countedterms/CountedTermsAggregator.java

@@ -13,6 +13,7 @@
 import org.apache.lucene.index.SortedDocValues;
 import org.apache.lucene.index.SortedSetDocValues;
 import org.apache.lucene.util.BytesRef;
+import org.elasticsearch.common.util.IntArray;
 import org.elasticsearch.common.util.LongArray;
 import org.elasticsearch.common.util.ObjectArray;
 import org.elasticsearch.core.Releasables;
@@ -26,6 +27,7 @@
 import org.elasticsearch.search.aggregations.InternalOrder;
 import org.elasticsearch.search.aggregations.LeafBucketCollector;
 import org.elasticsearch.search.aggregations.LeafBucketCollectorBase;
+import org.elasticsearch.search.aggregations.bucket.terms.BucketAndOrd;
 import org.elasticsearch.search.aggregations.bucket.terms.BucketPriorityQueue;
 import org.elasticsearch.search.aggregations.bucket.terms.BytesKeyedBucketOrds;
 import org.elasticsearch.search.aggregations.bucket.terms.InternalTerms;
@@ -38,7 +40,6 @@
 import java.util.Arrays;
 import java.util.Map;
 import java.util.function.BiConsumer;
-import java.util.function.Supplier;
 
 import static java.util.Collections.emptyList;
 import static org.elasticsearch.search.aggregations.InternalOrder.isKeyOrder;
@@ -115,51 +116,57 @@ public InternalAggregation[] buildAggregations(LongArray owningBucketOrds) throw
             LongArray otherDocCounts = bigArrays().newLongArray(owningBucketOrds.size());
             ObjectArray<StringTerms.Bucket[]> topBucketsPerOrd = bigArrays().newObjectArray(owningBucketOrds.size())
         ) {
-            for (long ordIdx = 0; ordIdx < topBucketsPerOrd.size(); ordIdx++) {
-                int size = (int) Math.min(bucketOrds.size(), bucketCountThresholds.getShardSize());
-
-                // as users can't control sort order, in practice we'll always sort by doc count descending
-                try (
-                    BucketPriorityQueue<StringTerms.Bucket> ordered = new BucketPriorityQueue<>(
-                        size,
-                        bigArrays(),
-                        partiallyBuiltBucketComparator
-                    )
-                ) {
-                    StringTerms.Bucket spare = null;
-                    BytesKeyedBucketOrds.BucketOrdsEnum ordsEnum = bucketOrds.ordsEnum(owningBucketOrds.get(ordIdx));
-                    Supplier<StringTerms.Bucket> emptyBucketBuilder = () -> new StringTerms.Bucket(
-                        new BytesRef(),
-                        0,
-                        null,
-                        false,
-                        0,
-                        format
-                    );
-                    while (ordsEnum.next()) {
-                        long docCount = bucketDocCount(ordsEnum.ord());
-                        otherDocCounts.increment(ordIdx, docCount);
-                        if (spare == null) {
-                            checkRealMemoryCBForInternalBucket();
-                            spare = emptyBucketBuilder.get();
+            try (IntArray bucketsToCollect = bigArrays().newIntArray(owningBucketOrds.size())) {
+                // find how many buckets we are going to collect
+                long ordsToCollect = 0;
+                for (long ordIdx = 0; ordIdx < owningBucketOrds.size(); ordIdx++) {
+                    int size = (int) Math.min(bucketOrds.bucketsInOrd(owningBucketOrds.get(ordIdx)), bucketCountThresholds.getShardSize());
+                    bucketsToCollect.set(ordIdx, size);
+                    ordsToCollect += size;
+                }
+                try (LongArray ordsArray = bigArrays().newLongArray(ordsToCollect)) {
+                    long ordsCollected = 0;
+                    for (long ordIdx = 0; ordIdx < owningBucketOrds.size(); ordIdx++) {
+                        // as users can't control sort order, in practice we'll always sort by doc count descending
+                        try (
+                            BucketPriorityQueue<StringTerms.Bucket> ordered = new BucketPriorityQueue<>(
+                                bucketsToCollect.get(ordIdx),
+                                bigArrays(),
+                                order.partiallyBuiltBucketComparator(this)
+                            )
+                        ) {
+                            BucketAndOrd<StringTerms.Bucket> spare = null;
+                            BytesKeyedBucketOrds.BucketOrdsEnum ordsEnum = bucketOrds.ordsEnum(owningBucketOrds.get(ordIdx));
+                            while (ordsEnum.next()) {
+                                long docCount = bucketDocCount(ordsEnum.ord());
+                                otherDocCounts.increment(ordIdx, docCount);
+                                if (spare == null) {
+                                    checkRealMemoryCBForInternalBucket();
+                                    spare = new BucketAndOrd<>(new StringTerms.Bucket(new BytesRef(), 0, null, false, 0, format));
+                                }
+                                ordsEnum.readValue(spare.bucket.getTermBytes());
+                                spare.bucket.setDocCount(docCount);
+                                spare.ord = ordsEnum.ord();
+                                spare = ordered.insertWithOverflow(spare);
+                            }
+                            final int orderedSize = (int) ordered.size();
+                            final StringTerms.Bucket[] buckets = new StringTerms.Bucket[orderedSize];
+                            for (int i = orderedSize - 1; i >= 0; --i) {
+                                BucketAndOrd<StringTerms.Bucket> bucketAndOrd = ordered.pop();
+                                buckets[i] = bucketAndOrd.bucket;
+                                ordsArray.set(ordsCollected + i, bucketAndOrd.ord);
+                                otherDocCounts.increment(ordIdx, -bucketAndOrd.bucket.getDocCount());
+                                bucketAndOrd.bucket.setTermBytes(BytesRef.deepCopyOf(bucketAndOrd.bucket.getTermBytes()));
+                            }
+                            topBucketsPerOrd.set(ordIdx, buckets);
+                            ordsCollected += orderedSize;
                         }
-                        ordsEnum.readValue(spare.getTermBytes());
-                        spare.setDocCount(docCount);
-                        spare.setBucketOrd(ordsEnum.ord());
-                        spare = ordered.insertWithOverflow(spare);
-                    }
-
-                    topBucketsPerOrd.set(ordIdx, new StringTerms.Bucket[(int) ordered.size()]);
-                    for (int i = (int) ordered.size() - 1; i >= 0; --i) {
-                        topBucketsPerOrd.get(ordIdx)[i] = ordered.pop();
-                        otherDocCounts.increment(ordIdx, -topBucketsPerOrd.get(ordIdx)[i].getDocCount());
-                        topBucketsPerOrd.get(ordIdx)[i].setTermBytes(BytesRef.deepCopyOf(topBucketsPerOrd.get(ordIdx)[i].getTermBytes()));
                     }
+                    assert ordsCollected == ordsArray.size();
+                    buildSubAggsForAllBuckets(topBucketsPerOrd, ordsArray, InternalTerms.Bucket::setAggregations);
                 }
             }
 
-            buildSubAggsForAllBuckets(topBucketsPerOrd, InternalTerms.Bucket::getBucketOrd, InternalTerms.Bucket::setAggregations);
-
             return buildAggregations(Math.toIntExact(owningBucketOrds.size()), ordIdx -> {
                 final BucketOrder reduceOrder;
                 if (isKeyOrder(order) == false) {

server/src/main/java/org/elasticsearch/search/aggregations/bucket/terms/BucketPriorityQueue.java

@@ -13,17 +13,17 @@
 
 import java.util.Comparator;
 
-public class BucketPriorityQueue<B> extends ObjectArrayPriorityQueue<B> {
+public class BucketPriorityQueue<B> extends ObjectArrayPriorityQueue<BucketAndOrd<B>> {
 
-    private final Comparator<? super B> comparator;
+    private final Comparator<BucketAndOrd<B>> comparator;
 
-    public BucketPriorityQueue(int size, BigArrays bigArrays, Comparator<? super B> comparator) {
+    public BucketPriorityQueue(int size, BigArrays bigArrays, Comparator<BucketAndOrd<B>> comparator) {
         super(size, bigArrays);
         this.comparator = comparator;
     }
 
     @Override
-    protected boolean lessThan(B a, B b) {
+    protected boolean lessThan(BucketAndOrd<B> a, BucketAndOrd<B> b) {
         return comparator.compare(a, b) > 0; // reverse, since we reverse again when adding to a list
     }
 }

server/src/main/java/org/elasticsearch/search/aggregations/bucket/terms/BucketSignificancePriorityQueue.java

@@ -12,14 +12,14 @@
 import org.elasticsearch.common.util.BigArrays;
 import org.elasticsearch.common.util.ObjectArrayPriorityQueue;
 
-public class BucketSignificancePriorityQueue<B extends SignificantTerms.Bucket> extends ObjectArrayPriorityQueue<B> {
+public class BucketSignificancePriorityQueue<B extends SignificantTerms.Bucket> extends ObjectArrayPriorityQueue<BucketAndOrd<B>> {
 
     public BucketSignificancePriorityQueue(int size, BigArrays bigArrays) {
         super(size, bigArrays);
     }
 
     @Override
-    protected boolean lessThan(SignificantTerms.Bucket o1, SignificantTerms.Bucket o2) {
-        return o1.getSignificanceScore() < o2.getSignificanceScore();
+    protected boolean lessThan(BucketAndOrd<B> o1, BucketAndOrd<B> o2) {
+        return o1.bucket.getSignificanceScore() < o2.bucket.getSignificanceScore();
     }
 }